This apparently is the closet that Peter will give to a tut so i thought it wise to post here so that we all know where it is There are some great versions of his sketch scattered around the photo art site, there are some
here,
here and
here
anyway this is his workflow in his own words
Here is what I have done (very quickly so not perfect)
1 dupe
2 Shadow highlight
3 Palms sketch action (faded 50%) set blend mode to multiply
...